If your car had original motor (as mine did) I'd pull the lot, sit it in the shed and do a rebuild at your leasure while still having fun with an L28 in the car. i was lucky, my parts car had a strong L28 and didn't have to do anything to it except change the oil and wack on the 240 carbs. Now I can give it a bit of a hiding without worrying about blowing the original motor. Took me and mate Friday night and then by lunch time Saturday we were driving, this was engine swap and manual conversion. Good luck with whatever you decide.